Spin configuration in a frustrated ferromagnetic/antiferromagnetic thin film system

TL;DR

This study investigates the complex magnetic configurations in ultrathin Mn films on Fe(001), revealing how steps induce magnetic frustration and how the magnetic wall width remains constant across different film thicknesses.

Contribution

It combines experimental spin-polarized STM and ab-initio calculations to analyze noncollinear magnetism and frustration in ultrathin antiferromagnetic films on a ferromagnetic substrate.

Findings

Magnetic frustration occurs around surface steps in Mn films.

The magnetic wall width remains constant up to seven monolayers.

Mn's weaker magnetic coupling results in less frustration compared to Cr.

Abstract

We have studied the magnetic configuration in ultrathin antiferromagnetic Mn films grown around monoatomic steps on an Fe(001) surface by spin-polarized scanning tunneling microscopy/spectroscopy and ab-initio-parametrized self-consistent real-space tight binding calculations in which the spin quantization axis is independent for each site thus allowing noncollinear magnetism. Mn grown on Fe(001) presents a layered antiferromagnetic structure. In the regions where the Mn films overgrows Fe steps the magnetization of the surface layer is reversed across the steps. Around these defects a frustration of the antiferromagnetic order occurs. Due to the weakened magnetic coupling at the central Mn layers, the amount of frustration is smaller than in Cr and the width of the wall induced by the step does not change with the thickness, at least for coverages up to seven monolayers.